Correct spark plug for KZ750 L3 with Kerker pipe?

I took my head in to a shop to get some work done. I learned a ton in the process, but that's all in a different thread. Along with the head, it seems I left the plugs with the shop and now I don't have them anymore.

The parts list at kz.mbsween.com/parts.html / kz.mbsween.com/parts/C-11Ignition.jpg suggests a few options, starting with B7ES.

Does anyone have one of these with a Kerker exhaust (I think this was an available option in '83)?

I recently had the thing rejetted, so all should be tuned to the exhaust, but I wonder which plugs I should get? I saw a couple threads suggesting B7ES as the go-to... Maybe I should get them as a baseline and then go up to B8ES if they aren't hot enough?

Have I mentioned that I love kzrider.com?

B7es is hotter then B8es is hotter then B9es

B8es would be my choice.Most KZ's were factory specs. with this heat range.If running temp is excessive and/or preignition try B9's

On a small cylinder the B7 is the right plug. I wouldn't go to a B8 until you start getting close to 900 The smaller the bore the hotter the plug. The KZ1300 also used the B6 plug because of the 62mm bore. The idea is, to use the hottest plug that you can, that will not cause detonation.

otakar wrote:

On a small cylinder the B7 is the right plug. I wouldn't go to a B8 until you start getting close to 900 The smaller the bore the hotter the plug. The KZ1300 also used the B6 plug because of the 62mm bore. The idea is, to use the hottest plug that you can, that will not cause detonation.

B7's are the stock plug for the KZ650,62 mm bore.
Is the KZ1300 water cooled?

FSM specifies B8ES for KZ750, Z1, Z2, KZ900, KZ1000, and KZ1100

After posting this, I found out that the Clymer manual says B8 for normal weather and B7 for cold temp (I'm in Seattle, so, not cold). The manual doesn't know about the Kerker pipes, but I guess that's not too big a deal. For now I'm planning on the B8ES. They're both within range, and I think I'd rather slowly melt a set of plugs than risk detonation (just looked it up) and have to get a new set in a few days. I guess either one would work..

Here's almost 5 years later. I've been running B8ES for a while, and it's been alright. I do a lot of desert riding.